1. Field of the Invention
The present invention relates to a battery, a device, and a charger.
2. Description Of Related Art
Devices, such as electronic devices, household electrical appliances, and small machine tools including power tools, can contain batteries (battery packs) for supplying operating power to device bodies. In such a device, a mechanism for detecting the voltage of a battery to notify a user of battery management information including the residual capacity, life, or the like of the battery is incorporated. Moreover, a charger also utilizes the voltage of a battery as the battery management information when the charger charges the battery. Such battery management information can be obtained from a charge/discharge management device mainly constituted by a microcomputer incorporated in a battery (e.g., refer to Japanese Patent Application Laid-open Publication No. 2000-350371 (FIG. 9)).
However, as described in the aforementioned related art, for acquiring the battery management information, the microcomputer is incorporated in the battery (battery pack). Therefore, this becomes an obstacle to miniaturization and price reduction of the battery.
On the other hand, charge/discharge characteristics and capacities of batteries differ depending on a manufacturer even if the batteries are of the same standard, and differ depending on lots even if the batteries have been fabricated by the same manufacturer, and therefore have minute individual variations due to slight non-uniformity in manufacturing even if the batteries are from the same lot. Moreover, even if batteries have the same shape, they may be batteries of different types (e.g., a nicad battery and a nickel metal hydride battery). Furthermore, batteries of a pirated copy, which are not authorized products of manufacturers, can be on the market. In addition, charge/discharge characteristics and capacities of batteries change depending on the time length from shipment until the batteries are actually used and the condition of storage section. Further, the charge/discharge characteristics and capacities of the batteries change during the repetition of charge and discharge after the batteries have actually started being used.
As described above, when batteries having different charge/discharge characteristics and capacities are loaded into a device or a charger to be discharged or charged, it is not at all sufficient to capture only voltages of the batteries as battery management information to be used on the device or charger side.
Specifically, devices and chargers are required to be precisely adjusted for discharge or charge operations in order to make the most of the performance of batteries. In addition, there are cases where desirable batteries for devices and chargers are assumed in advance, and therefore it is also necessary to detect the case where unexpected batteries have been loaded.